Inclined plane

ABSTRACT

Apparatus for determining weight components of mass on inclined plane acting perpendicular and parallel to incline comprises adjustable inclined plane with mass supported upon plane. Forceapplying structure is provided for forcing mass in upward direction perpendicular to inclined plane until mass just moves away from plane. Force-applying structure also forces mass in upward direction parallel to inclined plane until mass just moves in that direction.

United States Patent Chambers [451 Jan. 25, 1972 154] INCLINED PLANE[72] Inventor: Robert F. Chambers, 504 Beverly Road,

Newark, Del. 19711 [22] Filed: May 5, 1970 [21] Appl. No.2 34,750

Related U.S. Application Data [63] Continuation-impart of Ser. No.735,259, June 7,

1968, Pat. No. 3,520,981.

[52] U.S. Cl. ..35/l9 R [51] Int. Cl. ..G09b 23/06 [58] Field ofSearch..35/19R;273/l21 A, 86 B; 33/206 R [56] References Cited UNITED STATESPATENTS 1,935,674 11/1933 Smith ..33/206 R Lemelson ..273/12l A OTHERPUBLICATIONS Knott Apparatus Co. Catalog, pp. 1 17, l 18 only, receivedJan. 1917 Welch Scientific Co. Catalog, pg. 82 only, received Oct. 1965Primary Examiner-Harland S. Skogquist AtrorneyConnolly and Hutz [5 7]ABSTRACT Apparatus for determining weight components of mass on inclinedplane acting perpendicular and parallel to incline comprises adjustableinclined plane with mass supported upon plane. Force-applying structureis provided for forcing mass in upward direction perpendicular toinclined plane until mass just moves away from plane. Force-applyingstructure also forces mass in upward direction parallel to inclinedplane until mass just moves in that direction.

5 Claims, 5 Drawing Figures ril /H PATENTEDJMSIBYZ 3535340 SHEET 1 [IF 2PMEWIED WSW SHEET 2 0F 2 INCLINE!) PLANE CROSS-REFERENCE TO RELATEDAPPLICATION The present application is a continuation-in-partapplication of applicant's copending application Ser. No. 735,259, filedJune 7, I968 and now U.S. Pat. No. 3,520,98 I.

BACKGROUND OF THE INVENTION The present invention relates to apparatusfor classroom physics experiments, and more particularly to an apparatusfor demonstrating the forces associated with a mass on an incline.

Prior to the present invention numerous structural arrangements havebeen proposed for the purpose of demonstrating phenomena associated withthe classroom instruction of physics. Several arrangements have beenproposed for specifically demonstrating the forces associated with amass on an incline. However, for the most part, these arrangements arecharacterized by their complex mode of operation as well as the expenseof their overall construction. Financially, most of these arrangementsare beyond the reach of many school systems, and their complex natureresults in lack of interest on the part of the students. Often, studentslose interest during an inclined plane experiment because of the lengthyprocedures necessary to achieve a desired result. Thus, the teachingprofession has long sought equipment for inclined plane experimentswhich is reliable, inexpensive and simple to use.

Accordingly, it is an object of the present invention to avoid the abovedisadvantages and provide an apparatus for demonstrating the forcesassociated with a mass on an incline, the apparatus being simple tooperate and maintain as well as inexpensive and reliable.

SUMMARY OF THE INVENTION In accordance with the present invention anapparatus is provided for determining the weight components of a mass onan inclined plane acting perpendicular and parallel to the incline ofthe plane. The apparatus includes an adjustable inclined plane and amass which is supported upon the plane. Structure is provided forapplying a force to the mass in an upward direction perpendicular to theinclined plane until the mass just moves away from the plane. Structureis also provided for applying force to themass in an upward directionparallel to the inclined plane until the mass just moves in thatdirection.

In one embodiment of the present invention the mass includes front andrear wheels engaging the inclined plane, and the mass is constructed ofelectrically conductive material. The inclined plane may include anelectrically conductive strip upon which the wheels of the mass rest. Anelectrically conductive stop on the strip prevents the mass from ridingdown the incline. A series electrical circuit interconnects the massstop, and strip, and an indicator is provided in the circuit forindicating a break therein when the mass is out of contact with the stopand the strip.

In another embodiment of the present invention the mass comprises aframework with a horizontal cylindrical support member secured theretoand arranged to engage the inclined plane for supporting the mass uponthe plane. Weights are adjustably secured to the framework for adjustingthe center of gravity of the mass so that it lies along the longitudinalaxis of the horizontal cylindrical support member. The net effect isthat the size of the mass is reduced to the dimensions of the horizontalsupport member. The only requirement for the surface area of theinclined plane is that it be large enough to support the horizontalmember.

The horizontal cylindrical support member may include roller bearings.Also, the structure for applying force to the mass in an upwarddirection perpendicular to the inclined plane may include a lugrotatably mounted upon the horizontal support member. The lug functionsas an attaching device for securing a force to the mass that acts in adirection perpendicular to the inclined plane. Moreover, the mass mayinclude first and second pointers arranged at right angles to oneanother for aligning the direction of the force-applying structure sothat forces are applied in directions perpendicular and parallel to theinclined plane. A third pointer attached and parallel to the incline ofthe plane cooperates with either the first or second pointer to ensurethat the forces are applied perpendicular and parallel to the incline ofthe plane.

BRIEF DESCRIPTION OF THE DRAWING.

Novel features and advantages of the present invention in addition tothose mentioned above will become apparent to those skilled in the artfrom a reading of the following detailed description in conjunction withthe accompanying drawing wherein:

FIG. 1 is a front elevational view of an inclined plane apparatusaccording to the present invention;

FIG. 2 is a diagram of the force associated with the apparatus of FIG.1;

FIG. 3 is a front elevational view of another inclined plane apparatusaccording to the present invention;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3; and

FIG. 5 is a fragmental front elevational view of another inclined planeapparatus according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 1 and 2 illustrate aninclined plane apparatus 200 according to the present invention. Inessence, the apparatus 200 is utilized for determining the weightcomponents of a mass 202 on an inclined plane 204 which components actperpendicular and parallel to the incline of the plane. The inclinedplane 204 comprises a base member 206 with a plane member 208 hingedthereto at 210. The upper end of the plane member 208 carries a level212 for determining the approximate level of thev plane and making anynecessary adjustments. The angle of inclination of the plane member 208is set by a pair of struts 214 hinged at their lower ends to the basemember 206 and adjustably secured to the plane 208 by fasteners 216, oneon each side of the plane member. The inclined plane 204 rests on asupport table 218 with the rear side of the base member 206 flushagainst a guide plate 220 anchored to the support table.

A pair of support rods 222, 224 are secured to the support table 218 onopposite sides of the inclined plane 204. Each rod carries a pulley 226adjustably secured thereto. The apparatus 200 also includes anadjustable protractor 228 connected to a movable support 230. Anotherprotractor 232 is anchored to the under portion of the plane member 208for determining the angle of incline of the plane.

The mass 202 has front and rear wheels 234 and 236, respectively, whichrest upon a pair of spaced apart electrically conductive strips 238, andis maintained in equilibrium by an electrically conductive stop member240 fixed to the strips 238, as shown in FIG. 1. The mass 202 includingthe front and rear wheels is formed of electrically conductive material.Moreover, a series electrical circuit 242 interconnects an indicatorlamp 244 and power source 246 with the mass 202, strips 238 and stop240. As can readily be understood, when the wheels of the mass are incontact with either the strips 238 or the stop 240 the indicator lamp244 is energized but when the wheels are out of contact with both thestrips and stop the circuit is broken and the indicator lamp does notlight.

The present inclined plane apparatus 200 operates in the followingmanner to determine the weight components of a mass on an inclined planewhich components act perpendicular and parallel to the incline. First,the inclination of the plane member 208 is set at any arbitrary anglewhich angle is indicated by the protractor 232. When the plane member208 is level the fasteners 216 are tightened to securely anchor thestruts 214 to the plane member. The mass 202 is then positioned on theinclined plane 204 in static equilibrium with its wheels 234 and 236resting on the electrically conductive strips 238. Moreover, the frontwheels 234 of the mass 202 abut the stop 240.

The next step involves the application of force F to the mass 202 in adirection perpendicular to the incline of the plane. This isaccomplished by a string 248 or similar flexible member attached to themass at 249 and extending upwardly and over the pulley 226 on thesupport rod 222. The proper angle of the string 248 is obtained in thefollowing manner. First, the protractor 228 is adjusted to an angleequal to the angle of inclination of the plane. The support 230 for theprotractor is then moved into position so that the edge of theprotractor is directly beneath the string 248. While pressing the basemember 206 of the inclined plane 204 against the guide plate 220 theinclined plane is moved laterally until the edge of the protractor 228is parallel to the string 248. When this condition is satisfied, thestring is perpendicular to the inclined member 208 of the plane 204.Weights 250 are then applied to the string 248, in a manner describedbelow.

Force F l is applied to the mass 202 in a direction parallel to theincline of the plane 204. This is accomplished by a string 252 anchoredto the mass at 253 and extending upwardly over the pulley 226 on thesupport rod 224. The string 252 is made parallel to the inclined member208 by adjusting the pulley 226 on rod 224 until the string is parallelto the inclined member 208. Weights 254 are then attached to the end ofthe string 252, in a manner described below.

Preferably, forces F and F are gradually increased by hanging weights,such as 250 and 254, from the strings 248 and 252 until the force F isslightly less than that needed to lift the mass 202 free of the inclinedplane 204, and the force F 1 is just large enough to pull the frontwheels 234 of the mass away from the stop 240, as detected by the eye.Under these conditions, the indicator lamp 244 is energized. Force I isthen gradually increased until the indicator lamp goes out. Thisindicates that the mass 202 is out of contact with the electricallyconductive strips 238 and the stop 240. Next, the force F, is graduallyreduced until the indicator lamp lights, which indicates that the frontwheels 234 of the mass have contacted the stop 240 to complete thecircuit. The last adjustment of force F l is followed by an increase inforce F until the indicator lamp goes out. The weights applied tostrings 248 and 252 are then measured and compared with the theoreticalvalues computed by utilizing the actual weight of the mass and theincline of the plane.

FIGS. 3 and 4 illustrate another embodiment of the present invention fordetermining the weight of components of a mass 300 on an adjustableinclined plane 302. As in the embodiment illustrated in FIGS. 1 and 2,the weight components determined act perpendicular and parallel to theincline of the plane. The adjustable inclined plane 302 has an inclinedportion 204 with a right angle stop portion 306 connected thereto. Theseportions of the inclined plane are adjustably secured to a horizontalsupport 308 connected by a clamp 310 to a support rod 312. The supportrod is anchored to a base member 314. The angle of inclination of theinclined portion 304 is made adjustable by the locking connection 316 inthe horizontal support 308.

The mass 300 includes a framework 318 having a horizontal cylindricalsupport member 320 secured thereto and arranged to engage the inclinedplane for supporting the mass upon the plane, as shown in the drawing.The cylindrical support member 320 has rotatable bearings 322 thatengage the inclined plane 302. Weights 325, 326 and 328 are adjustablysecured to. the framework 318 for adjusting the center of gravity of themass so that it lies along the longitudinal axis of the horizontalcylindrical member 320 at a location midway between the long sides ofthe framework. The weights 324 and 326 are adjustable in both horizontaland vertical directions when the wheels 330 of the mass 300 are restingupon a horizontal support. By appropriately adjusting the weights 324and 326 the horizontal and vertical coordinates of the center of gravityof the mass 300 are made to coincide with the longitudinal axis of thehorizontal cylindrical support member 320. Weight 328 is manipulated toadjust the third coordinate of the center of gravity of the mass 300 sothat it is midway between the long sides of the framework 318.

A lug 332 is rotatably secured to the horizontal cylindrical supportmember 320 at a position midway between the long sides of the framework318 which position is between the roller bearings 322. As explained morefully below, the lug 332 has an opening therein for attaching a forcewhich is perpendicular to the incline of portion 304. A second lug 334is rotatably secured to the framework 318 of the mass 300 for thepurpose of attaching a second force to the mass 300 which is parallel tothe incline of the portion 304. The lug 334 is positioned so that thedirection of a correct force applied thereto passes through the centerof gravity of the mass 300.

A pair of pointers 336 and 338 arranged at right angles to one anotheris secured to the framework 318 of the mass 300. The pointer 336cooperates with a pointer 340 on the inclined plane 302. The pointer 336is horizontally disposed when the wheels of the framework 318 of themass 300 rest upon a horizontal support. The pointer 340 on the inclinedplane is parallel to the incline of the portion 304. Accordingly, whenthe pointers 336 and 340 are in alignment the mass 300 can be said to bepositioned at an inclination equal to the incline of the plane. Pointer338 on the framework 318 serves as a reference for applying a force tothe mass 300 which acts perpendicular to the incline of the plane.

Support rods 342, 344, adjustable pulleys 346, 348, strings 350, 352,and weights 354 and 356 are provided for applying forces to the mass 300for the purpose of measuring the component forces of the mass 300 whichact perpendicular and parallel to the incline of the plane.

In operation, the base member 314 which serves to support the inclinedplane 302 is positioned upon a support table 358 so that the support rod312 attached to the base 314 is approximately midway between the supportrods 342 and 344. For reasons explained more fully below, the base 314is positioned against a guide plate 360 anchored to the support table358. In the next step the locking connection 316 is released and theangle of inclination of the inclined plane is set to any arbitraryvalue. The locking connection 316 is then tightened to fix theinclination at the arbitrary value. The mass 300 is supported upon theinclined plane 302 by the horizontal cylindrical support member. Theroller bearings of the horizontal support member engage the portions 304and 306 of the inclined plane. The mass is rotated about the axis of thehorizontal support member 320 until the pointer 336 is directly oppositethe pointer 340 on the inclined plane 302. Force is then applied to themass by attaching weights 354 to the string 350 connected to the mass300 by the lug 334. When the string is taut the pulley 346 is movedvertically on its support rod 342 until the pointers 336 and 340 areapproximately in coincidence. Weights 356 are then attached to string352 until that string is taut. The base support member 314 is thenshifted laterally while in engagement with the stationary guide plate360 until the pointers 336 and 340 are in exact coincidence. Theprotractor and plumb bob assembly 362 secured to the framework 318 nowregisters the angle of inclination of the plane, which angle is 30 inthe example illustrated in the drawing. The pulley 348 is adjustedvertically on its support rod 344 until the string 352 is parallel tothe pointer 338. When the above conditions are satisfied the directionof the forces applied to the mass 300 are perpendicular and parallel tothe incline of the plane. The weights 354 and 356 are then increaseduntil the mass 300 is out of contact with the inclined plane 302. Theweights applied to the strings 350 and 352 are then measured andcompared with the theoretical values computed by utilizing the actualweight of the mass and the incline of the plane.

Preferably, the framework 318 of the mass 300 as well as the adjustableinclined plane 302 are constructed of electrically conductive material.The horizontal cylindrical support member 320 is also constructed ofsimilar material. A series electrical circuit 364 interconnects anindicator lamp 366 and power source 268 with the framework 318, supportmember 320 and the adjustable inclined plane 302. As can readily beunderstood, when the support member 320 is in contact with the inclinedplane 302 the indicator lamp 366 is energized but when the member 320 isout of contact with the inclined plane 302 the circuit is broken and theindicator lamp does not light. The circuitry of the embodiment of theinvention illustrated in H08. 3 and 4 may be utilized in the same manneras described above in conjunction with the embodiment of the inventionillustrated in FIGS. 1 and 2.

The present inclined plane apparatus enables one to accurately measurethe components of a mass which act perpendicular and parallel to theincline of a plane. The horizontal cylindrical support 302 is surroundedby the overall mass 300. The efi'ect is to reduce the size of the massto the dimensions of the horizontal support member and reduce the sizeof the plane to that of a postage stamp.

An alternate apparatus for measuring the weight components of mass 300which act perpendicular and parallel to the incline of portion 304 is toinclude roller bearings 370 with the portions 304 and 306 of theinclined plane 302, as shown in FIG. 5. The roller bearings 322associated with the horizontal cylindrical support 320 of the apparatusof FIGS. 3-4 are replaced by a pair of rotatably mounted rectangularblocks 372. The blocks 372 may be locked in position after the pointers336 and 340 are brought into alignment.

What is claimed is:

1. Apparatus for determining the weight components of a mass on aninclined plane acting perpendicular and parallel to the incline of theplane comprising an adjustable inclined plane, a mass including aframework having a horizontal cylindrical support member secured theretowith its longitudinal axis passing through the center of gravity of themass and arranged to engage the inclined plane for supporting the massupon the plane, means for applying forces to the mass in an upwarddirection perpendicular to the incline of the plane and in an upwarddirection parallel to the incline of the plane, and indicator meansassociated with the mass for indicating when the forces applied theretoare perpendicular and parallel to the incline of the plane.

2. Apparatus as in claim 1 wherein the indicator means includes firstand second pointers displaced from one another for aligning thedirection of the force-applying means whereby forces may be applied indirections perpendicular and parallel to the incline of the plane.

3. Apparatus as in claim 2 including a third pointer fixed relative tothe inclined plane and arranged in a direction parallel to the inclineof the plane, the third pointer cooperating with one of the otherpointers whereby when these two pointers are in exact alignment with oneanother one of the forces applied to the mass acts parallel to theincline of the plane.

4. Apparatus as in claim 1 wherein the mass and the inclined plane areconstructed of electrically conductive material and the inclined planeincludes and electrically conductive stop for preventing the horizontalcylindrical support member from sliding down the incline, and a serieselectrical circuit interconnecting the mass, incline and stop, thecircuit including means for indicating a break therein when the mass isout of contact with the stop and the incline.

5. Apparatus as in claim 1 wherein the horizontal cylindrical supportmember includes a bearing member having a circular cross section.

1. Apparatus for determining the weight components of a mass on aninclined plane acting perpendicular and parallel to the incline of theplane comprising an adjustable inclined plane, a mass including aframework having a horizontal cylindrical support member secured theretowith its longitudinal axis passing through the center of gravity of themass and arranged to engage the inclined plane for supporting the massupon the plane, means for applying forces to the mass in an upwarddirection perpendicular to the incline of the plane and in an upwarddirection parallel to the incline of the plane, and indicator meansassociated with the mass for indicating when the forces applied theretoare perpendicular and parallel to the inclinE of the plane.
 2. Apparatusas in claim 1 wherein the indicator means includes first and secondpointers displaced 90* from one another for aligning the direction ofthe force-applying means whereby forces may be applied in directionsperpendicular and parallel to the incline of the plane.
 3. Apparatus asin claim 2 including a third pointer fixed relative to the inclinedplane and arranged in a direction parallel to the incline of the plane,the third pointer cooperating with one of the other pointers wherebywhen these two pointers are in exact alignment with one another one ofthe forces applied to the mass acts parallel to the incline of theplane.
 4. Apparatus as in claim 1 wherein the mass and the inclinedplane are constructed of electrically conductive material and theinclined plane includes and electrically conductive stop for preventingthe horizontal cylindrical support member from sliding down the incline,and a series electrical circuit interconnecting the mass, incline andstop, the circuit including means for indicating a break therein whenthe mass is out of contact with the stop and the incline.
 5. Apparatusas in claim 1 wherein the horizontal cylindrical support member includesa bearing member having a circular cross section.